A High Court judge is set to rule over a challenge by a family that the investigation into the shooting of barrister Mark Saunders by police is unlawful.
Mr Justice Underhill was told at the hearing last month that the Independent Police Complaints Commission (IPCC) inquiry was flawed because officers involved in the siege at the lawyer's Chelsea flat were allowed to confer before recording their accounts.
Tim Owen QC, representing sister Charlotte Saunders who brought the case, told the court the issue was whether this was compatible with human rights laws.
He said: "There can be no doubt that the present practice means that there is a substantial risk of collusion and of contamination."
Mr Owen added: "On the facts of the claimant's case the risk is substantial. The officers were not separated before their accounts were obtained.
"The opportunity to confer and therefore the risk of collusion was increased by a number of events. There was a delay in providing initial statements. The Metropolitan Police Commissioner has now admitted that there was in fact conferring between the officers."
He said the IPCC had provided further opportunity to confer by organising meetings attended by groups of officers to put the questions to them.
Miss Saunders and her family, who believe the barrister was posing no further risk when he was shot, also sought a declaration from Mr Justice Underhill that there had been an unlawful failure to disclose sufficient information in the course of the investigation into the shooting on May 6 this year.
Mr Saunders, 32, died of multiple bullet wounds after a five-hour shootout with police at his luxury Chelsea flat.
Mr Saunders, who worked as a divorce lawyer, died after shooting at police officers, neighbours and buildings with a legally-owned shotgun from his £2.2 million Markham Square flat.
